If you want a single external integration to have push access to all projects, you don't need a service account in every namespace. You can create a single service account, and grant that service account push access to all namespaces.

But now we have the following question:Is there a way to create a global service account which is automatically generated when we create a new project. (so that we have 4 default sa).And this service account has automatically a pusher-token which is always the same?

So that every login via Jenkins can use the same token (no unique token for each openshift project).